1. Field of the Invention
The present invention relates generally to the field of starters for machinery. More particularly, the present invention concerns start circuits that prevent re-engagement of a starter while the machine is running. Specifically, a preferred embodiment of the present invention is directed to push button starters that include a latching anti-restart circuitry. The present invention thus relates to a start circuits of the type that can be termed latching.
2. Discussion of the Related Art
Heretofore, it was known in the prior art to employ an automotive starter switch which allows a one shot start function. A conventional automotive starter switch typically requires that the switch be cycled back through the off position to re-enable the start function. Previously recognized problems with these types of automotive starter switches are that such switches are unreliable and easily broken. Further, automotive starter key switches are impossible to seal. As with any key type switch, water can enter through the key opening. Water ingression can lead to corrosion of the terminals and subsequent malfunction. Furthermore, automotive starter switches are not fool-proof and can be easily tricked. For example by quickly turning the switch off, and then on again, the start function can be re-enabled even though the engine is still running. What is needed therefore is a starter with an anti-restart feature that is reliable and mechanically robust. Such a switch should be capable of being sealed against water. Additionally, the anti-restart feature of such a switch should not be avoidable through manual manipulation. Heretofore these requirements have not been fully met without incurring various disadvantages.
One previously recognized solution to the problem of providing a reliable sealed unavoidable switch was to use a timer that prevents re-engagement of a push button for 10-15 seconds after the button is released. A disadvantage of this previously recognized solution is that it does not prevent re-engagement while the engine is running so long as the required period has elapsed. This previous solution was not a closed loop system.
The below-referenced U.S. patents disclose embodiments that were at least inpart satisfactory for the purposes for which they were intended but which had certain disadvantages. The disclosures of all the below-referenced prior United States patents in their entireties are hereby expressly incorporated by reference into the present application for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
U.S. Pat. No. 4,570,583 discloses an engine starter protecting device. An electromagnetic switch which controls the starter motor is opened as soon as the output from a series of detectors departs from a predetermined status.
U.S. Pat. No. 4,907,562 discloses a method for achieving an elevated charge of an ignition capacitor in a capacitive type ignition system. Recharging of a capacitor is delayed until the position of the crankshaft corresponds to the lowest voltage drop in the electrical system.
U.S. Pat. No. 5,195,476 discloses a method and apparatus for preventing wear in an internal combustion engine. A delay element prevents actuation of one or both of the fuel pump and the spark plug for a predetermined time interval or until pressure at the oil pump reaches a predetermined level.